Graded levels of Eimeria infection modulated gut physiology and temporarily ceased the egg production of laying hens at peak production

Abstract

An experiment was conducted to investigate the changes in gastrointestinal physiology, including intestinal leakage, immune response, oxidative stress, along with performance traits, of Hy-Line W-36 laying hens following Eimeria infection at peak egg production. A total of 360 laying hens, at 25 wk of age, were assigned randomly to 5 treatment groups, each consisting of 6 replicate cages, including a nonchallenged control group. The other 4 groups were inoculated with graded levels of mixed Eimeria species as high, medium-high, medium-low, and low doses, respectively. The body weight (BW) and body weight gain (BWG) of laying hens were measured from 0 to 14 days postinoculation (DPI). Average daily feed intake (ADFI) and hen-day egg production (HDEP) were measured from 0 to 15 and 0 to 28 DPI, respectively. Gut permeability was measured on 5 DPI, whereas oxidative stress, immune response, and expression of nutrient transporter genes were measured on 6 and 14 DPI. A significant linear reduction in BW and BWG was observed with increased Eimeria inoculation dosage on both 6 and 14 DPI (P < 0.001, P-Lin < 0.0001). An interaction between the Eimeria dosages and DPI was observed for ADFI (P < 0.0001). Feed intake in the challenged groups decreased starting at 4 DPI, with the most significant drop occurring at 7 DPI, which did not recover until 15 DPI. Following the challenge, gastrointestinal physiology shifted toward the host defense against the Eimeria infection by upregulating mRNA expression of tight junction proteins and immune responses while downregulating the expression of key nutrient transporters on 6 and 14 DPI (P < 0.05). An interaction between the Eimeria inoculation dosage and DPI was also observed for daily HDEP (P < 0.0001). Overall, HDEP was lower in the challenged groups compared to the control. Daily HDEP in the challenged groups dropped from 8 DPI and became similar to the control birds only after 24 DPI. Egg production temporarily ceased in most of the laying hens infected with the high and medium-high dosages of Eimeria. In conclusion, Eimeria infection activated the host immune response, negatively affecting the gastrointestinal health, growth performance, and temporarily ceased the egg production of Hy-Line W-36 laying hens when infected at peak production.

Keywords: coccidiosis; gastrointestinal health; hen-day egg production; laying hens; oxidative stress.

Figure 1

Effect of different dosage of mixed Eimeria (E. maxima, E. acervulina, and E. tenella) challenge on average daily feed intake from 0 to 27 DPI. The different treatment groups were Control: Nonchallenge Control, Low: the low-dose treatment (6,250 E. maxima; 6,250 E. tenella; and 31,250 E. acervulina sporulated oocysts per mL), the Med-Low treatment (12,500 E. maxima; 12,500 E. tenella; and 62,500 E. acervulina sporulated oocysts per mL), the Med-High treatment (25,000 E. maxima; 25,000 E. tenella; and 125,000 E. acervulina sporulated oocysts per mL), and the high-dose treatment (50,000 E. maxima, 50,000 E. tenella, and 250,000 E. acervulina sporulated oocysts per mL). DPI: days postinoculation.

Figure 2

Effect of different dosage of mixed Eimeria (E. maxima, E. acervulina, and E. tenella) challenge on daily hen-day egg production from 0 to 28 DPI. The different treatment groups were Control: Nonchallenge Control, Low: the low-dose treatment (6,250 E. maxima; 6,250 E. tenella; and 31,250 E. acervulina sporulated oocysts per mL), the Med-Low treatment (12,500 E. maxima; 12,500 E. tenella; and 62,500 E. acervulina sporulated oocysts per mL), the Med-High treatment (25,000 E. maxima; 25,000 E. tenella; and 125,000 E. acervulina sporulated oocysts per mL), and the high-dose treatment (50,000 E. maxima, 50,000 E. tenella, and 250,000 E. acervulina sporulated oocysts per mL); DPI: days postinoculation.

Figure 3

Effect of different dosage of mixed Eimeria (E. maxima, E. acervulina, and E. tenella) challenge on daily hen-day egg production from 25 to 28 wk of age. The different treatment groups were Control: nonchallenge control, Low: the low-dose treatment (6,250 E. maxima; 6,250 E. tenella; and 31,250 E. acervulina sporulated oocysts per mL), the Med-Low treatment (12,500 E. maxima; 12,500 E. tenella; and 62,500 E. acervulina sporulated oocysts per mL), the Med-High treatment (25,000 E. maxima; 25,000 E. tenella; and 125,000 E. acervulina sporulated oocysts per mL), and the high-dose treatment (50,000 E. maxima, 50,000 E. tenella, and 250,000 E. acervulina sporulated oocysts per mL); DPI: days postinoculation.

Figure 4

Effect of different dosage of mixed Eimeria (E. maxima, E. acervulina, and E. tenella) challenge on feed conversion ratio (kg of feed per dozen of eggs) from 25 to 28 wk of age. The different treatment groups were Control: nonchallenge control, Low: the low-dose treatment (6,250 E. maxima; 6,250 E. tenella; and 31,250 E. acervulina sporulated oocysts per mL), the Med-Low treatment (12,500 E. maxima; 12,500 E. tenella; and 62,500 E. acervulina sporulated oocysts per mL), the Med-High treatment (25,000 E. maxima; 25,000 E. tenella; and 125,000 E. acervulina sporulated oocysts per mL), and the high-dose treatment (50,000 E. maxima, 50,000 E. tenella, and 250,000 E. acervulina sporulated oocysts per mL); DPI: days postinoculation.

Figure 5

Effect of different dosage of mixed Eimeria (E. maxima, E. acervulina, and E. tenella) challenge on gastrointestinal permeability measured by fluorescein isothiocyanate dextran. The different treatment groups were Control: nonchallenge control, Low: the low-dose treatment (6,250 E. maxima; 6,250 E. tenella; and 31,250 E. acervulina sporulated oocysts per mL), the Med-Low treatment (12,500 E. maxima; 12,500 E. tenella; and 62,500 E. acervulina sporulated oocysts per mL), the Med-High treatment (25,000 E. maxima; 25,000 E. tenella; and 125,000 E. acervulina sporulated oocysts per mL), and the high-dose treatment (50,000 E. maxima, 50,000 E. tenella, and 250,000 E. acervulina sporulated oocysts per mL); DPI: days postinoculation.

Figure 6

Effect of different dosage of mixed Eimeria (E. maxima, E. acervulina, and E. tenella) challenge on lesion score in upper intestine, mid intestine, and ceca of Hy-Line W-36 laying hens on 6 DPI. The different treatment groups were Control: nonchallenge control, Low: the low-dose treatment (6,250 E. maxima; 6,250 E. tenella; and 31,250 E. acervulina sporulated oocysts per mL), the Med-Low treatment (12,500 E. maxima; 12,500 E. tenella; and 62,500 E. acervulina sporulated oocysts per mL), the Med-High treatment (25,000 E. maxima; 25,000 E. tenella; and 125,000 E. acervulina sporulated oocysts per mL), and the high-dose treatment (50,000 E. maxima, 50,000 E. tenella, and 250,000 E. acervulina sporulated oocysts per mL.

Figure 7

Effect of different dosage of mixed Eimeria (E. maxima, E. acervulina, and E. tenella) challenge on the oxidative status (TAC, total antioxidant capacity; MDA: malondialdehyde, GSH, glutathione; GSSG, glutathione disulfide) of Hy-Line W-36 laying hens on 6 DPI. The concentration of TAC was measured from serum, whereas liver tissue was used to measure the concentration of MDA, GSH, and GSSG. The different treatment groups were Control: nonchallenge control, Low: the low-dose treatment (6,250 E. maxima; 6,250 E. tenella; and 31,250 E. acervulina sporulated oocysts per mL), the Med-Low treatment (12,500 E. maxima; 12,500 E. tenella; and 62,500 E. acervulina sporulated oocysts per mL), the Med-High treatment (25,000 E. maxima; 25,000 E. tenella; and 125,000 E. acervulina sporulated oocysts per mL), and the high-dose treatment (50,000 E. maxima, 50,000 E. tenella, and 250,000 E. acervulina sporulated oocysts per mL; DPI: days postinoculation.